Aggregation of rod-coil block copolymers containing rigid polyampholyte blocks in aqueous solution

Rod-coil block copolymers containing rigid polyampholyte blocks were designed and synthesized by RAFT copolymerization. The rigid polyampholyte blocks were formed by hydrolysis of alternating copolymers of N,N,N',N'-tetraethyl-4,4'-diaminostilbene with maleic anhydride, and the flexible coil block consists of poly(oligo(ethylene glycol)methacrylate). The rod-coil block copolymers form polyion complex (PIC) aggregates even when the polyampholyte blocks are charge imbalanced. The aggregates did not dissociate upon the addition of high concentrations of NaCl unlike the dissociation of flexible polyampholytes in NaCl solution. These unique solution properties are induced by like-charge attractions of the rigid polyampholytic alternating copolymer chains.